The invention relates to a sensor arrangement for direct or indirect optical determination of physical or chemical parameters, comprising an indicator cell, which is permeable to the chemical substance or physical quantity to be measured and contains one or more indicators, and further comprising a radiation source supplying the excitation radiation for the indicator, and a detector for detection of the response radiation emitted by the indicator, in which contact between the radiation source and the indicator, or the indicator and the detector is exclusively established via the excitation radiation and the response radiation.